The Philippines expressed concern on Monday about China’s testing of a massive dredging ship, saying it would track its activities closely, despite Beijing’s assurances it would not develop areas where it has competing claims with Manila.

China, which has poured billions of dollars into building artificial islands to strengthen its sovereignty claims across most of the South China Sea, has started testing a new ship designed to boost its land reclamation capability.

“The mere presence is a little bit concerning,” defence secretary Delfin Lorenzana said. “Where it is going, we do not know.”

Military officials said the ship, Tian Kun Hao, had a deck the size of nine basketball courts and would become Asia’s largest dredging vessel.

China claims almost the entire South China Sea, through which more than US$3 trillion worth of trade passes each year. Brunei, Malaysia, the Philippines, Taiwan and Vietnam also have conflicting claims in the area.

Lorenzana said troops deployed on nine Philippine-claimed features in the South China Sea had been ordered to monitor the movements of Chinese navy, coastguard and fishing boats in the Spratly Islands.

“We are constantly monitoring the movement of the ship,” he said. “We have also our air patrol going regularly, so we will be able to monitor movement of this so-called very big dredger ship.”

The testing of the dredger comes ahead of two major international meetings in Vietnam and the Philippines this week and next, which are to be attended by China and the United States.

In August, the foreign ministers of Southeast Asia and China adopted a negotiating framework for a code of conduct in the South China Sea, a move they hailed as progress but which critics saw as a tactic to buy China time to consolidate its maritime power.

All parties said the framework was only an outline for how the code would be established, but critics said the failure to outline as an initial objective the need to make the code legally binding and enforceable, or have a dispute resolution mechanism, raised doubts about how effective it would be.

In Beijing, China’s assistant foreign minister Chen Xiaodong said talks on the framework had achieved important progress and that there would be results at the Manila summit of Southeast Asian nations.

“Whether the code is binding, or how it would be binding, and what the code looks like in its final form, depends on the outcome of the talks between China and the Association of Southeast Asian Nations,” Chen said. “It can’t be decided by a single party.”